研究了TiAl金属间化合物的组织结构和氢化物含量对屈服强度σ_(ys),解理断裂强度σ_F以及断裂韧性K_(Ic)的影响.结果表明,对单相γ,随等轴晶粒尺寸降低,σ_(ys)和σ_F略有升高,如出现层状结构(α+γ2两相),则σ_(ys),σ_F和K_(Ic)明显上升,氢化物使σ_(ys)上升但使K_(Ic)下降,层状结构的氢脆敏感性要比等轴γ的小. 合金中解理裂纹形核的阻力随着裂纹的扩展而不断增大,呈现稳态扩展,跟踪裂纹的形核和扩展,发现当裂尖塑性区及其变形量发展到临界值后,解理裂纹在塑性区中沿滑移带形核。
Effects of microstructure and hydrides contained on yield strength, σ_(ys), critical fracture strength, σ_F, and fracture toughness, K_(Ic), of TiAI alloy have been studied. Results show that σ_(ys) and σ_F increase slightly with size reduction of equiaxial grains of single phase γ. Yet σ_(ys), σ_F and K_(Ic) increase substantially if lamellar structure of bi-phase γ+α_2 occurred. Hydride may cause the increase of σ_(ys) and the decrease of K_(Ic). The suscepitibility for lamellar structure to hydrogen embrittlement may be lower than that for the equiaxial single phase γ. Resistance to cleavage-like crack initiation in TiAl alloy increases gradually with as steady-state propagation of crack. When plastic zone at crack tip and deformation developed up to critical value, the cleavage-like cracks initiate along slip band in plastic zone.
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